1. Field of the Invention
The present invention relates to an image forming apparatus of an electrophotographic type or an electrostatic recording type such as a copying machine, a laser beam printer and the like, and a fixing apparatus mounted to such an image forming apparatus.
2. Related Background Art
In a fixing apparatus mounted to an image forming apparatus such as a laser beam printer, generally, a pressure roller is urged against a fixing roller (fixing rotary member) having a heater therein to form a fixing nip therebetween, and, while a recording material bearing a non fixed toner image is being passed through the fixing nip, by heat and pressure, the non fixed toner image is fixed onto the recording material as a permanent image.
Further, the fixing roller normally has a mechanism for coating or applying a mold releasing agent (oil) to prevent toner offset and to improve a mold releasing ability.
In such mold releasing agent coating mechanisms, it is known to provide a system in which an oil supplying pump is used to supply oil to an oil dripping pipe from which the oil is in turn dripped onto a cleaning felt or a fixing roller, and the oil is uniformly coated on the fixing roller by a regulating blade, and excessive oil is passed through the regulating blade and is collected in an oil pan for re-use.
However, the above-mentioned system in which the oil is regulated by the regulating blade is greatly influenced by the viscosity of the oil.
For example, in the case of oil having high viscosity, a larger amount of oil tends to pass through the regulating blade, thereby increasing the oil coating amount. Further, the viscosity of oil is varied with a temperature of the oil, and, particularly, when the viscosity of the oil is great immediately after replenishment of oil, the oil coating amount is increased. In this way, the oil coating becomes unstable.